pabst etal



Feb. 14, 1956 P. F. PABST ET AL 2,734,454

SHEET EDGE TRIMMER FOR PRINTING PRESSES 4 Sheets-Sheet 1 Filed Oct. 15, 1954 R. y mg m Wm mm PW Y B 1 w F A TTORNZY Feb. 14, 1956 P. F. PABST ET AL 2,734,454

SHEET EDGE TRIMMER FOR PRINTING PRESSES 4 Sheets-Sheet 2 Filed Oct. 15, 1954 INVENTOR. Ph/l/p F. Pubs? BY W/l/l'am H. Conway A TTORNEY' Feb. 14, 1956 P. F. PABST ET AL 2,734,454

' SHEET EDGE TRIMMER FOR PRINTING PRESSES Filed Oct. 15, 1954 4 Sheets-Sheet 3 D INVENTOR. v Phi/1p 1-". Pubs? w A TTOR/YEY Feb. 14, 1956 P, F. PABST ETAL 2,734,454

SHEET EDGE TRIMMER FOR PRINTING PRESSES Filed Oct. 15, 1954 4 Sheets-Sheet 4 INVENTOR. Phi/ ,0 F Pabsf BY W////am H. Conway A TTOR/VZ'Y United States Patent a 2,734,454 SHEET EDGE TRIMMER FOR PRINTING PRESSES Philip F. Pabst, Hamden, and William H. Conway, New Haven, Conn., assignors, by mesne assignments, to Federal Paper Board Company, Inc., Bogota, N. 3., a corporation of New York Application October 15, 1954, Serial No. 462,594

8 Claims. (Cl. 101-246) This invention relates to the art of making paper boxes from printed sheets of paperboard and relates particularly to the machine operations of printing and the subsequent cutting and creasing of the printed sheets prior to separation of the sheets into individual box blanks from which paper boxes are then formed.

' This invention deals particularly with improvements in mechanisms for insuring perfect register of the sheet with successive printing plates and with the cutting and creasing die, so that not only the various color imprints register perfectly, but that also the cuts and the creases produced by the die occur in the proper places with regard to the printing.

Imperfect register between the various colors and between the printing and the cuts and creases produced by the die is largely due to the difficulty of clamping the sheets in identical position on the cylinders of the several presses through which the sheets run. I

I In some cases only a single color imprint may be involved which is then followed by the cutting and creasing operation performed on a different press. In the event the sheets are multi-colored, it may be necessary to run the sheets through two, or possible more, printing presses and thereafter through the cutting and creasing press. In the latter case the likelihood of errors in the register are increased, and imperfect register in only one of the several presses may be sufficient to make the sheet unfit for use. a I There are three major causes for imperfect register. The leading edge of the sheet may be irregular in that it may be concave, convex, or wavy. The leading edge, even it perfectly straight may be slightly out of square with the side edge of the sheet. Finally, the leadingedge of successive sheets may be such as to produce different degrees of rebound of the sheet from the stop, sometimes also called drop guide, which arrests the sheet before being grasped by the grippers of the cylinder.

Printing presses, as well as cutting and creasing presses, are usually of the cylinder type and they comprise a cylinder, or a plurality of cylinders, to which the sheets are clamped as they pass through the machine. 7 A feeding mechanism feeds the sheets towards the first cylinder where each sheet is arrested when its lea-ding edge strikes one or several stops or drop guides. A gripping mechanism then grasps the sheet near its leading edge and clamps it against gripper pads which form extensions of the cylinder surface.

' The most commonly used form of gripper is a fingerlike device mounted on an oscillating gripper shaft on the cylinder. This shaft is usually mounted in a trough in the cylinder surface and generally extends parallel to the cylinder axis. Mechanism is provided on the presses for oscillating this shaft in one direction in order to move the gripper towards the cylinder surface in order to clamp the sheet thereon, and in the opposite direction for releasing the sheet.

Each gripper finger is usually associated with a gripper pad equipped with a friction surface against which the "Ice finger bears. The gripper pads are generally bolted to clamping devices on a stationary shaft in the trough. This arrangement permits any number of gripper fingers to be installed in any desired position with a corresponding number of gripper pads opposite the fingers. Generally the fingers and their cooperating pads are evenly spaced along the shafts, the most common spacing of the fingers being three and one-half inches. This spacing has been found most satisfactory for clamping the sheets securely.

The prior Patent 2,645,995 of July 21, 1953, discloses and claims a device for locally trimming the leading edge of a sheet in such a way as to provide not only for uniform distance of the trimmed edge from the imprint but also for uniform physical characteristics of the edge, so that sheets fed at the same velocity rebound uniformly, or not at all, from the stops or drop guides which they encounter in the various presses.

This invention deals with certain inventive improvements and the refinements of edge trimming devices of the character disclosed and claimed in the aforementioned patent.

In the printing of multi-colored sheets it is frequently desirable to associate the key form, or key plate, not with the first, but with the second or third cylinder of the printing press. The key plate is the printing plate which carries that portion of the imprint which is critical in the register of the imprint with the cutting and creasing die. The key plate is usually a plate which carries considerable detail, such as legends which have to occur in an accurately defined area or portions of the design such as bands, lines, or other outlines which have to match at the cor ners of the completed box.

The sequence of printing of the various colors is determined by the nature of the subject to be printed and also the nature and character of the inks used. For this reason it is not always practical to associate the key plate with the first cylinder but it may be desirable to associate it with a subsequent cylinder. It is generally desirable to perform the edge trimming operation in connection with the imprint of the key plate and, therefore, by a cylinder other than the first cylinder.

. For this reason it is desirable to have a trimming device which may be associated with any of several cylinders and which may be moved from one cylinder to am other with little difliculty each time the press is set up for a new job.

It is also desirable to have a trimming device which is so designed that it can be installed on cylinders of standard construction Without modification or machining of the cylinder proper.

It is further desirable to have a trimming device which may be moved to any position along the entire length of the trough so as to accommodate large sheets requiring Widely spaced trimming knives and narrow sheets requiring narrowly spaced knives.

It is finally desirable to have a trimming device which is so constructed that it will not interfere with the operation of the grippers, nor with their spacing and which Will not reduce the number of points at which the sheet is gripped, nor alter the normal spacing of these points.

' The invention provides an improved edge trimming device which fulfills the various aforementioned specific requirements and is equally suited for cylinder presses of the fiat bed type and for cylinder presses of the rotary type.

The aforementioned, and various other objects, features and advantages of the invention will appear more fully from the detailed description which follows, accompanied by drawings showing, for the purpose of illustration, a preferred form of the invention and a convenient manner of its installation and use.

The invention also consists in certain new and original features of construction and combination of elements hereinafter set forth and claimed.

Although the characteristic features of this invention which are believed to be novel will be particularly pointed out in the claims appended hereto, the invention itself, its objects and advantages, and the manner in which it may be carried out, may be better understood by referring to the following description taken in connection with the accompanying drawings forming part of it in which:

Fig. l is a perspective view of a portion of a press cylinder including gripping devices and an edge trimmer embodying the invention, the grippers being shown in open position.

Fig. 2 is a perspective view of the cylinder portion with the grippers in closed position.

Fig. 3 is an exploded perspective view of a preferred form of edge trimmer assembly embodying the invention.

Fig. 4 is a perspective view of a gripper pad and a supporting clamp for supporting the pad on a fixed mounting shaft.

Fig. 5 is a perspective view of the supporting clamping device of Fig. 4, the gripper pad proper being removed and replaced by a knife assembly.

Fig. 6 is side view, partly in section, of a peripheral portion of a machine cylinder including the trimming knife and a corresponding portion of a flat bed including a striking plate opposite the knife; and

Fig. 7 is a plan view of a portion of the leading edge of a sheet after cutting of an accurate abutment edge, but prior to the removal of the strip of stock exposing the edge.

In the following description and in the claims various details will be identified by specific names for convenience. The names, however, are intended to be as generic in their application as the art will permit. Corresponding reference characters refer to corresponding parts in the several figures of the drawings.

In the drawings accompanying and forming part of this specification certain specific disclosure of the invention is made for the purpose of explanation of broader aspects of the invention, but it is understood that the details may be modified in various respects without departure from the broad principles of the invention and that the invention may be practiced by other means and be applied to other structures than the ones shown.

The press cylinder 10 has a longitudinal trough 11 in its cylinder surface 12. A gripper shaft 13 is pivotally mounted in the end walls of the trough, one such end wall being visible in the illustration at 14. are mounted on the gripper shaft 13 at substantially regular intervals. The most advantageous spacing of grippers has been found by experience to be of the order of three and one-half inches. Each gripper comprises a gripper body 16 from which a finger 17 extends. The finger 17 is slightly resilient and has a serrated undersurface 18 at its end adapted to bear against an equally serrated gripper pad 19 which is mounted in a position in which it forms an extension of the cylindrical surface 12. The individual grippers are held on the gripper shaft by means of set screws 20 permitting longitudinal as well as angular adjustment of the individual grippers.

The pivotal mounting on the gripper shaft permits the shaft to be oscillated into one extreme position which is shown in Figure l in which the gripper fingers are fully disengaged from the gripper pads 19. In the opposite extreme position, illustrated in Figure 2, the gripper fingers 17 bear against the gripper pads 19 with considerable force. The force is exerted by a spring 21 in an operating linkage 22 of the gripper shaft which causes oscillation of the shaft in timed relation with the rotation of the cylinder. The operating mechanism for the gripper shaft is conventional and it does not form part of the present invention and it is suificient to state that the gripper shaft is oscillated periodically so as to clamp Grippers 15 4 sheets and release them at predetermined clock-dial positions during rotation of the cylinder 10.

A fixed shaft 23 is mounted in the cylinder trough substantially parallel to the gripper shaft and somewhat closer to the leading edge 24 of the cylinder surface 12, the direction of rotation of the cylinder being indicated by the arrow 25. The shaft 23 is non-rotatable and serves as a convenient means for supporting the gripper pads 19 by means of appropriate mountings at predetermined points along the leading edge 24.

A convenient form of supporting device for the gripper pads is shown in Figures 4 and 6 in greater detail. The supporting device is essentially a clamp 26 slotted at 27 to permit tightening by a bolt 28. The supporting device has an extension or arm 29 which includes a. hole (not visible) near its end through which hole a bolt 30 extends for securing the gripper pad 19 to the arm. The hole is preferably larger than the diameter of the bolt 30 to permit adjustment of the top surface 31 of the gripper pad relatively to the central axis of the fixed mounting shaft 23.

The adjustment of the gripper pads is facilitated by a polygonal eccentric cam 32 held on a stub shaft 33 by means of a pin 34. The cam surfaces have different distances from the center of the cam. Rotation of the cam permits any one of the surfaces to be brought underneath the bottom surface of the gripper pad, whereafter the bolt 30 is tightened to secure the pad in its adjusted position with regard to the axis of the fixed shaft 23. The illustrated and described gripper pad and its supporting device or clamp 26 are of conventional construction.

Sheets are fed toward the cylinder in a substantially tangential direction into a position in which they overlap the gripper pads 19. If the cylinder is the first cylinder of the press, the sheets are usually arrested by one or several moveable stops or drop guides which move into and out of the path of the sheet in timed relationship with the operation of the press. Such a stop or drop guide is shown in the aforementioned Patent 2,645,995. If the cylinder under consideration is not the first cylinder on the press, the sheet is delivered to it by a transfer cylinder on the press which delivers the sheet with great accuracy without any stops on or near the cylinder 10.

For the purpose of explanation of the invention it may be assumed that the illustrated cylinder 10 is the second or the third cylinder of the press, and that the sheet is delivered to it by a transfer cylinder in a conventional manner. It may also be assumed that the illustrated cylinder is associated with the key plate carrying the critical design of the imprint, the key plate being visible in Figure 6 at 35.

The improved edge trimming device embodying the invention trims the leading edge of the delivered sheet at a predetermined point or points along the leading edge in accurate relationship with a key plate 35.

A suitable form of trimming device is shown in Figure 3. It comprises a base plate 36 having two mounting holes 37 and 38 extending from front to back of the base plate. These holes may be tapped or plain, depending on the type of mounting device for the gripper pads. In the illustrated embodiment the holes are tapped to fit bolts similar to, or identical with the bolts 30 which normally secure the gripper pads to the supporting devices 26. The preferred spacing of the holes 37 and 38 is of the order of three and one-half inches, that is equal to the normal spacing of the gripper fingers and gripper pads on the printing press.

The base plate 36 has a top surface 39 which is serrated at 40 and 41 to provide friction surfaces of the same nature as the top surfaces 31 of the gripper pads. A ledge 42 extends substantially parallel to the top surface 39 and serves to support the blunt bottom edge 43 of a knife blade 44 to be mounted on the base plate 36. The knife blade 44 is substantially U-shaped and comprises 5 a substantially flat bight portion 45 from which the two short legs 46 and 47 extend at an angle to form the U.

The base plate 36 of the knife mount is correspondingly recessed at its central portion 48 to receive the U-shaped knife blade 44. Two tapped holes 49 and 50 are provided for bolts 51 and 52 extending through holes 53, 54 of the same spacing in a clamping plate 55 and holes 56 and 57 in the blade 44.

The knife blades 44 are replaceable and are so dimensioned that the sharp top edge 58 extends a predetermined distance above the friction surfaces 40 and 41 of the base plate 36 when the bottom edge 43 of the blade rests on the ledge 42. This arrangement provides for uniformity among all the knife assemblies and permits one assembly to be exchanged for another without requiring readjustment. It also permits a dull or broken blade to be replaced without subsequent readjustment.

Figure 5 shows the supporting device or clamp 26 of Figure 4 after removal of the gripper pad 19 and replacement by a knife assembly.

Referring now to Figure 1 it is seen that the first two pairs of gripper points for the sheet are formed by gripper fingers 17 and opposite gripper pads 19. The next two gripped points are formed by gripper fingers which coopcrate, with the friction surfaces 40 and 41 of a knife assembly inserted in place of the two gripper pads which were removed. It is readily seen that neither the position northe spacing of the grippers is altered in any way to accommodate the trimmer. It is equally apparent that the knife assembly could be inserted opposite the second and third gripper fingers or, in fact, opposite any other pair of adjacent grippers of the cylinder.

As also stated in the aforementioned Patent 2,645,995 sheet trimming devices are commonly installed in pairs so that the leading edge of the sheet is trimmed at a certain distance, for example within four or ten inches, from both ends of the leading edge. It is, therefore, necessary to reset the trimming knives when sheets of greater or narrower width are run on the press. This is accomplislied with little difficulty according to the invention by simply removing a pair of adjacent gripper pads at the appropriate location and installing an edge trimming knife assembly in its place. The mounting of the knife blade then assumes the function of the gripper pads and the number of gripping points is not reduced nor is it necessary to make any changes in the position of the gripper fingers nor in the position of their supporting devices 26 on the fixed shaft 23.

Figure 6 shows the knife assembly in the position op posite the flat bed 59 carrying a striking plate 60 of hardened steel opposite the blade 44. From this figure it is evident that a U-shaped incision is made in every sheet on a cylinder at an accurate predetermined distance from critical lines or details on the key plate 35. No sheet is shown in Figure 6 for reasons of clarity, since the sheet would obstruct the view of the blade 44.

It is understood, however, that the sheet overlies the surface 12 and extends a short distance beyond the U legs 46 of the blade. This causes a thin strip of stock 61 to be partially severed adjacent the leading edge 62 of the sheet 63 as shown in Figure 7. The strip may then be removed by a conventional stripping operation. The trimmed edge 64 thus formed on the sheet bears an accurate relation with regard to the imprint produced by the key plate and is used for positioning the sheet by means of stops in subsequent operations for example in a subsequent printing press or in the cutting and creasing press.

What is claimed is:

1. In a cylinder printing press for printing sheets of paper, paperboard and box board, the press including a cylinder, and a counter-member for the cylinder adapted to support a printing plate, said cylinder having a longitudinal trough in its cylindrical surface, the combination of said cylinder; a gripper shaft mounted in said trough for oscillation; a plurality of gripper fingers on said gripper shaft; a plurality of gripper pads less in number than said fingers, said pads being mounted in said trough adjacent the cylinder surface opposite certain of said fingers, said fingers and pads constituting pairs of gripping points; a pair of clamping plates mounted in said trough, at least one of the plates of the pair having friction surfaces opposite other fingers to form two further pairs of gripping points with saidother fingers, a knife blade of substantially U-shape mounted between said plates, the bigt of the U being open towards said trough; and a striking plate opposite said blade on said counter-member.

' 2. A cylinder for printing presses for printing sheets of paper, paperboard and box board, the cylinder having a longitudinal trough in its cylinder surface; a gripper shaft mounted on said cylinder in said trough; a plurality of gripper fingers on said shaft; a plurality of gripper pads mounted in said trough adjacent the cylinder surface opposite certain of said gripper fingers, said fingers and pads constituting pairs of gripping points for sheets to be printed; a knife holder mounted in said trough, said knife holder having two friction surfaces opposite other gripper fingers, said other fingers and friction surfaces constituting further pairs of gripping points; and a knife blade of substantially U-shape in said -knife holder, the bight of the U being open toward said trough, the edge of the knife projecting above the friction surfaces of the holder.

3. A cylinder for printing presses for printing sheets of paper, paperboard and box board, the cylinder having a longitudinal trough in its cylinder surface; a first gripper shaft mounted on said cylinder in said trough with freedom of oscillation about the shaft axis; a second mounting shaft fixedly mounted in said trough; a plurality of gripper fingers mounted on said gripper shaft; a plurality of clamps mounted on said second shaft opposite said gripper fingers; a plurality of gri per'pads, said pads being secured to certain of said clamps opposite certain of said fingers and adjacent the cylinder surface, said certain fingers and pads constituting pairs of gripping points for sheets to be printed; a knife holder secured to other clamps, said other clamps forming an adjacent pair, said knife holder having two friction surfaces opposite other gripper fingers, said friction surfaces and other fingers constituting two further pairs of gripping points; and a knife blade of substantially U-shape in said knife holder, the bight of the U being open toward said trough, the edge of the knife projecting above the friction surfaces of the holder.

4. A cylinder for printing presses for printing sheets of paper, paperboard and box board, the cylinder having a longitudinal trough in its cylinder surface; a first gripper shaft mounted on said cylinder in said trough with freedom of oscillation about the shaft axis; a second mounting shaft fixedly mounted in said trough; a plurality of gripper fingers mounted on said gripper shaft; a plurality of clamps mounted on said second shaft opposite said gripper fingers; a plurality of gripper pads, said pads being secured to certain of said clamps opposite certain of said fingers and adjacent the cylinder surface, said certain fingers and pads constituting pairs of gripping points for sheets to be printed; a knife assembly secured to other clamps, said other clamps forming an adjacent pair, said assembly comprising, a base plate having two friction surfaces opposite other gripper fingers, said friction surface and said other fingers constituting two further pairs of gripping points, said base plate having a ledge substantially parallel to said friction surface; a clamping plate; means for securing said clamping plate to said base plate; and a knife blade of substantially U-shape resting on said ledge between said base plate and said clamping plate, the bight of the U being open toward said trough, the edge of the knife projecting above the friction surfaces of the base plate.

5. A cylinder for printing presses for printing sheets of paper, paperboard and box board, the cylinder having a longitudinal trough in its cylinder surface; a first gripper shaft mounted on said cylinder in said trough with freedom of oscillation about the shaft axis; a second mounting shaft fixedly mounted in said trough; a plurality of gripper fingers mounted on said gripper shaft; 21 plurality of clamps mounted on. said second shaft opposite said gripper fingers; a plurality of gripper pads, said pads being secured to certain of said clamps opposite certain of said fingers and adjacent the cylinder surface, said certain fingers and pads constituting pairs of gripping points for sheets to be printed; a knife assembly comprising a base plate having two mounting holes extending from front to back of the base plate, two tapped holes between said mounting holes, a top surface including two friction areas substantially above said mounting holes, and a ledge on the front surface below said tapped holes, the ledge being substantially parallel to said friction areas; a knife blade of substantially U-shape resting on said ledge, the edge of the knife projecting above the friction areas; a clamping plate overlying said blade; a pair of bolts for tightening said clamping plate against said base plate, thereby holding the knife in position; and a further pair of bolts extending through said mounting holes for securing the knife assembly to two other clamps forming an adjacent pair in a position in which said friction areas are opposite other gripper fingers, which other gripper fingers together with said friction areas constitute further pairs of gripping points.

6. A cylinder for printing presses for printing sheets of paper, paperboard and box board, the cylinder having a longitudinal trough in its cylinder surface; a gripper shaft mounted in said trough; a plurality of substantially evenly spaced gripper fingers on said shaft, a plurality of gripper pads mounted in said trough adjacent the cylinder surface opposite certain of said gripper fingers; and a knife assembly mounted in said trough adjacent the cylinder surface opposite other gripper fingers, said knife assembly comprising, a base plate having two friction surfaces opposite said other gripper fingers; a clamping plate; means for securing said clamping plate to said base plate; and a knife blade of substantially U-shape between said base plate and said clamping plate, the bight of the U being open toward the trough.

7. For use in a cylinder printing press equipped with gripping fingers and removable gripper pads opposite said gripping fingers, the combination of a pair of gripping fingers, and an edge trimming knife assembly comprising, a base plate having two mounting holes extending from front to back of the base plate, and having a top surface including two spaced knurled friction areas substantially above said mounting holes and opposite said pair of fingers; a knife blade of substantially U-shape; a clamping plate overlying said blade; and a pair of bolts for tightening said clamping plate against said base plate for holding the knife in a fixed position between the plates.

8. An edge trimming knife assembly for use in a cylinder printing press equipped with gripping fingers and removable gripper pads opposite said gripping fingers, said knife assembly being insertable in place of any two adjacent gripper pads and comprising, a base plate having end portions, and a recessed intermediate portion between the end portions, said intermediate portion comprising a bottom ledge, the end portions having two tapped holes therethrough extending from front to back, the top surface of said end portions being knurled, the intermediate portion having two tapped holes therethrough; a knife blade of substantially U-shape and of a height sufficient to protrude above the level of the knurled surface when resting on said ledge; a clamping plate overlying said blade and a pair of bolts extending through said clamping plate into the tapped holes in the intermediate portion for tightening said clamping plate against said base plate to hold the knife between the plates.

References Cited in the file of this patent UNITED STATES PATENTS 2,645,995 Isella July 21, 1953 

